package huawei;

import java.math.BigInteger;
import java.util.*;


public class T_T {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        int num = in.nextInt();
        BigInteger result = BigInteger.valueOf(1);
        // BigInteger bigNum = BigInteger.valueOf(num);
        for (int i = num; i >= 1; i-- ) {
            BigInteger tem = BigInteger.valueOf(i);
            result = result.multiply(tem);
        }

        Stack<Character> stack = new Stack<>();

        System.out.println(result);

        in.close();

    }
}